1. Field
The subject matter of the present application relates generally to a localizing unit for a diagnostic system at least partially covered with a sterile drape.
2. Description of the Related Art
Medical interventions involving living subjects are increasingly performed using navigation assistance provided by a navigation support system. In some navigation support systems, a surgical instrument is guided by means of a position detection system relative to a tissue region of the subject undergoing treatment. Navigation assistance is of particular interest in body regions that cannot be visually inspected by the surgeon, such as when the instrument is inserted into the interior of the subject. For this purpose, the instrument, for example, a catheter, is guided in a virtual 3D volume generated by means of an imaging method prior to or during surgery. For example, an X-ray diagnostic machine may be used to generate a series of 2D projection images having a known projection geometry, and the 2D images may be used to generate a 3D volume data set. The 3D volume data set is transmitted to the navigation system, which is equipped with a position detection system for detecting positions of the markers. For high-precision navigation, the coordinate system of the position detection system can be aligned and/or oriented with the coordinate system of the 3D volume data set in a process commonly known as “registration.”
Various X-ray diagnostic devices are known in which a portion of the device is provided with marks that can be detected by a position detection system.
German Patent DE 196 40 993 A1 (Offenlegungsschrift) describes a medical therapy and/or diagnosis device enclosed by a sterilization sheath. A sterilizable and operationally detachable mounting element is coupled above the sterilization sheath. The mounting element has an operating position on the medical therapy and/or diagnosis device such that a defined positional relationship is produced between the device and the mounting element. When the mounting element is coupled to the sterilization sheath, fitting pins penetrate the sheath and are held in fitting pin recesses. The mounting element can be used to fasten the sterilization sheath to the therapy and/or diagnosis device by a knurled-head screw.
U.S. Pat. No. 7,122,032 B2, an operating microscope with a sterile sheath is described. A sterilizable electrical plug connector is used to puncture the sterile sheath. The electrical plug connector has a flange that affixes the sterile sheath on the microscope housing.
German Patent DE 102 15 808 B4 describes an X-ray device having a mark arrangement on the holder for a C-arm. The mark arrangement can be detected with a position detection system, and the spatial configuration and position of the X-ray device can be determined.
German Patents DE 103 60 025 B4 and DE 101 39 329 B4 describe X-ray diagnosis devices in which an X-ray receiver has a mark arrangement.
German Patent DE 199 08 903 C2 describes a localizing unit for imaging and describes positioning devices, which have, on a base plate, marks and sensors for position detection with different localizing systems.
German Patent DE 196 25 411 C2 describes a medical unit having a detachable and displaceable handle and a sterile drape.
It is known from actual practice using localizing units for diagnostic devices with sterile drapes that a position detection system may have difficulty in detecting a localizing unit through the drape. Accordingly, in actual practice, a substantially transparent sterile drape is positioned close to the localizing unit. The drape may be temporarily affixed in position, as described, for example, in the second aspect of the invention of DE 196 40 993 A1. Such positioning disadvantageously may cause the sterile drape to be punctured with subsequent loss of sterility, particularly with localizing units or marks having small radii of curvature.
In implementations in which the localizing unit is held in the operating position, and the drape is positioned on the housing of the diagnostic device, the mechanical characteristics of the sterile drape in its actual orientation on the device may be accounted for when the position and orientation of the localizing unit is determined in the coordinate system of the diagnostic device. Mechanical characteristics may include, for example, thickness, compressibility, arrangement of folds, welding or seam edges, and so forth. In actual practice, such positioning may be difficult, because, for example, freedom from folds of the sterile drape can be controlled only with great difficulty in an area in which the drape is attached to the system.